http://www.ck12.org Chapter 7. Momentum Conservation
MEDIA
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- You jump off of the top of your house and hope to land on a wooden deck below. Consider the following
possible outcomes:
a. You hit the deck, but it isn’t wood! A camouflaged trampoline slows you down over a time period of 0. 2
seconds and sends you flying back up into the air.
b. You hit the deck with your knees locked in a straight-legged position. The collision time is 0.01 seconds.
c. You hit the deck and bend your legs, lengthening the collision time to 0.2 seconds.
d. You hit the deck, but it isn’t wood! It is simply a piece of paper painted to look like a deck. Below is an
infinite void and you continue to fall, forever.a. Which method will involve the greatest force acting on you?
b. Which method will involve the least force acting on you?
c. Which method will land you on the deck in the least pain?
d. Which method involves the least impulse delivered to you?
e. Which method involves the greatest impulse delivered to you?- You punch the wall with your fist. Clearly your fist has momentum before it hits the wall. It is equally clear
that after hitting the wall, your fist has no momentum. But momentum is always conserved! Explain. - You look up one morning and see that a 30 kg chunk of asbestos from your ceiling is falling on you! Would
you be better off if the chunk hit you and stuck to your forehead, or if it hit you and bounced upward? Explain
your answer. - A baseball player faces a 80.0 m/s pitch. In a matter of.020 seconds he swings the bat, hitting a 50.0 m/s
line drive back at the pitcher. Calculate the force on the bat while in contact with the ball. - A place kicker applies an average force of 2400 N to a football of 0.40 kg. The force is applied at an angle of
20 .0 degrees from the horizontal. Contact time is .010 sec.
a. Find the velocity of the ball upon leaving the foot.
b. Assuming no air resistance find the time to reach the goal posts 40.0 m away.
c. The posts are 4.00 m high. Is the kick good? By how much?- Your author’s Italian cousin crashed into a tree. He was originally going 36 km/hr. Assume it took 0. 40
seconds for the tree to bring him to a stop. The mass of the cousin and the car is 450 kg.